PROJECT SUMMARY/ABSTRACT One in five transgender women (TGW) in the U.S. is infected with HIV. The burden is particularly onerous for African Americans. While 16% of U.S. TGW are Black, over half of all new cases in TGW from 2009-2014 were among African Americans. Further, African American TGW experience a complex interaction of racism, sexism, and transphobia that leads to health disparities across the entire spectrum of HIV-related outcomes. Despite the clear need for effective HIV resources designed for African American TGW, no CDC-defined evidence-based interventions (EBIs) exist for this group. We intend to meet this need with Shine, a culturally- tailored, theoretically-driven mobile intervention for Black TGW. The Information-Motivation-Behavioral Skills (IMB) model will guide the development of behavior change messages tailored to a user?s HIV status. Beyond information, motivation, and skills, a unique socio-cultural context also influences TGW?s ability to perform HIV-related behaviors. To account for this, we will contextualize the IMB-based HIV content by addressing a key intrapsychic need among Black TGW: gender affirmation. According to the Model of Gender Affirmation, a need for gender identity validation often leads Black TGW to engage in behaviors that run counter to HIV prevention and treatment goals. To further improve HIV outcomes, Shine will teach healthy methods for gaining gender affirmation. By empowering Black TGW to affirm their gender in healthier ways, the goal is to create a context where HIV behavior change is most likely to be successful. Shine will be the first mobile intervention for African American TGW that is theory-based, individually- tailored, and empowering. All users will receive IMB-based informational, motivational, and skill-building text messages. Additional messaging will provide strategies for gaining gender affirmation. These text messages will be supplemented by three types of web-based videos: scripted vignettes, unscripted peer narratives, and educational instruction. Links to these videos will be integrated into the messaging and will enhance the trans- specific understanding of gender affirmation within our IMB framework. An innovative theory-based HIV behavioral intervention designed to overcome the unique barriers facing African American TGW, that addresses elements across the entire HIV care continuum, that is delivered in a way that empowers, educates, and engages a stigmatized population, and that relies on a technology that is part of the everyday lives of target end-users has the significant potential to meaningfully reduce HIV disparities. Sixteen African American TGW will be recruited for a focus group discussion to help shape the Shine intervention. Based on what we learn from these groups and our team of consultants, we will develop a prototype mobile intervention. When completed, the 16 African American TGW will return for usability testing. The usability test will include a series of tasks intended to highlight the features of the proposed intervention. Three usability metrics will be assessed: efficiency, accuracy, and subjective satisfaction.